1. Field of the Invention
The invention relates to a control apparatus for suitable use in aircraft such as a helicopter, vehicles, robot manipulators, data inputting apparatuses for computers, and the like.
2. Description of the Related Art
In a control apparatus having a back driving function for a control stick, it is possible to select one of modes including a trim mode in which the neutral point of the control stick is shifted by means of the back driving function, and a manual mode in which a back drive unit is disconnected and the control stick is subjected to a manual operation.
In the case where an electromagnetic brake mode is selected when the control stick is being operated, by operating an electromagnetic brake, the electromagnetic brake releases a part of movable components of the back drive unit which have been fixed. Then, the restoring force of a feel unit (spring) which has been displaced by movement of the control stick causes an output arm of the back drive unit and gears sequentially coupling an output shaft with the brake to start to rotate and have an inertial force. Even when the feel unit substantially returns to its natural length and the angle error between the control stick and the output shaft of the back drive unit becomes zero, the members continue to move due to the inertial effect of rotating components. As a consequence, the feel unit is displaced in the reverse direction to produce in the control stick an adverse transient such as an overshoot. When an elastic component such as a reaction force generating spring exists in a part of the back drive transmission system, an overshoot caused by elastic deformation is added to such a transient, and the resulting transient appears as a larger displacement.
As a countermeasure against such a transient, the following techniques are conventionally employed, namely, a) the gear ratio with respect to the brake mechanism is reduced so as to lower the number of rotation, or b) a damper mechanism is disposed in the reaction force generating spring so as to absorb the inertial energy.
In the prior art technique a), when the reduction ratio with respect to the brake mechanism is increased, the brake torque is increased although the number of rotation of the brake is lowered, and hence the size and weight of the brake mechanism are increased. In the prior art technique b), the damper mechanism must be additionally required, thereby increasing the size and weight of the control apparatus as a whole.
It is an object of the invention to provide a control apparatus in which the occurrence of an adverse transient during the operation of a brake can be surely prevented, and which can be reduced in size and weight and manufactured at a low cost.
The invention provides a control apparatus comprising:
a control section which is supported so as to be angularly displaceable to a housing;
a control amount sensor for detecting an angular displacement amount of the control section and outputting a control amount signal;
an elastic member for generating an operation force in accordance with the angular displacement amount based on a neutral point of the control section;
a back drive mechanism, coupled to the control section via the elastic member, for driving the control section to move the neutral point; and
a controlling section for controlling the back drive mechanism,
the back drive mechanism including a differential gear mechanism having a first input shaft, a second input shaft and an output shaft; a motor coupled to the first input shaft; a brake mechanism coupled to the second input shaft; and a driving member coupled to the output shaft, for driving the control section, and
wherein when the control section is being moved, the brake mechanism is put into disconnection to release the second input shaft, the back drive mechanism rotates the motor in a reverse direction in order to prevent occurrence of a transient.
According to the invention, in the case where when the control section is being moved, the brake mechanism is operated so as to release the second input shaft, the restoring force of the elastic member which has been displaced by movement of the control section causes gears sequentially coupling the output shaft of the back drive mechanism with the brake mechanism to start to operate or rotate, that is, have an inertial force. Since these members continue to operate or rotate due to the inertial effect of the rotating components even when the elastic member substantially returns to its natural length and the angle error between the control section and the output shaft should become zero, the elastic member is displaced in the reverse direction to produce a transient in the control section. When the motor is rotated in the reverse direction in order to prevent the occurrence of a transient, the speed of the inertia-induced operation of the output shaft, which causes a transient, can be lowered and the displacement due to the transient can be canceled by rotation of the motor. As a consequence an influence of the transient is prevented from being transmitted to the control section. At this time, it is preferable to select the rotation amount of the motor to coincide with a temporal change in the displacement of the output shaft which causes the transient. An influence of the transient can be eliminated more surely in this case.
Furthermore, The invention provides a control apparatus comprising:
a control section which is supported so as to be angularly displaceable to a housing;
a control amount sensor for detecting an angular displacement amount of the control section and outputting a control amount signal;
an elastic member for generating an operation force in accordance with the angular displacement amount based on a neutral point of the control section;
a back drive mechanism, coupled to the control section via the elastic member, for driving the control section to move the neutral point; and
a controlling section for controlling the back drive mechanism,
the back drive mechanism including a differential gear mechanism having a first input shaft, a second input shaft and an output shaft; a motor coupled to the first input shaft; a brake mechanism coupled to the second input shaft; a driving member coupled to the output shaft to drive the control section; and a back drive position sensor for detecting an angular displacement amount of the driving member and outputting a back drive position signal,
wherein when the control section is being moved, the brake mechanism is put into disconnection to release the second input shaft, the back drive mechanism temporarily stops the second input shaft by putting the brake mechanism into connection at a time when a relative displacement amount between the control amount signal and the back drive position signal becomes zero, in order to prevent occurrence of a transient.
According to the invention, in the case where when the control section is being moved, the brake mechanism is put into disconnection so as to release the second input shaft, the restoring force of the elastic member which has been displaced causes internal gears, the output shaft, and the driving member of the back drive mechanism to operate so as to follow the movement of the control section. At a time when the relative displacement amount between the control amount signal and the back drive position signal becomes zero, the brake mechanism is temporarily put into connection so as to stop the second input shaft, whereby the brake operates under a condition that the elastic energy accumulated in the elastic member is lost, with the result that the internal gears, output shaft and driving member of the back drive mechanism are stopped. Therefore, an overshoot can be eliminated and an influence of the transient can be further lowered.